Competitive interactions between various oligodeoxyribonucleotides and calf thymus DNA-dependent RNA polymerase type II are being characterized. Specificity of the enzyme for particular sequences has been demonstrated and found to reside in single stranded structures. DNA binding proteins from non infected cells and from cells infected by Herpes simplex virus (a known oncogenic virus) are being isolated and tested for their ability to preferentially bind to specific regions of HSV DNA. The effect of these proteins on the interaction of RNA polymerase with DNA is being evaluated.